Ethylene copolymers and their uses

ABSTRACT

The invention provides for ethylene copolymers having a polymodal CD, wherein under temperature rising elution fractionation (TREF) analysis the ethylene copolymers evidence at least two peaks.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a Continuation Application of, and claimspriority to U.S. Ser. No. 10/883,551, filed Jul. 1, 2004, now issued asU.S. Pat. No. 7,381,783, which is a Continuation Application of U.S.Ser. No. 10/696,680, filed on Oct. 29, 2003, now abandoned, which is aDivisional Application of U.S. Ser. No. 09/808,609 filed Mar. 14, 2001,now abandoned, which is a Divisional Application of, and claims priorityto U.S. Ser. No. 09/207,213, filed on Dec. 8, 1998, now issued as U.S.Pat. No. 6,248,845, which is a Continuation-in-Part application of U.S.patent application Ser. No. 08/986,696, filed Dec. 8, 1997, now issuedas U.S. Pat. No. 6,242,545

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to catalysts, catalyst systems and their use inolefin polymerization. The invention more particularly relates tosubstituted hafnium metallocene-type catalyst compounds, catalystsystems thereof, their use in a polymerizing process, their polymerproducts and articles thereof.

2. Description of the Related Art

The use of bulky ligand transition metal catalyst compounds inpolymerization processes to produce a diverse array of new polymers foruse in a wide variety of applications and products is well known in theart. Typical bulky ligand transition metal compounds, known asmetallocene-type compounds, are generally described as containing one ormore ligands capable of η-5 bonding to the transition metal atom,usually, cyclopentadienyl derived ligands or moieties, in combinationwith a transition metal selected from Group 4, 5 or 6 or from thelanthanide and actinide series of the Periodic Table of Elements.Predominantly in the literature the transition metal is from Group 4,particularly either titanium, zirconium or hafnium, and thecyclopentadienyl derived ligand or moiety is substituted with variousradicals, typically alkyl radicals, or two or more cyclopentadienylligands are joined by a structural bridge, usually an organic orinorganic group, typically, a carbon or silicon atom containing group.

Other forms of these metallocene-type catalyst compounds contain acyclopentadienyl derived ligand or moiety and a heteroatom containinggroup bonded to a transition metal, typically titanium, where thecyclopentadienyl ligand or moiety and the heteroatom containing groupare joined by a structural bridge, usually a silicon atom containinggroup. These and other metallocene-type catalyst compounds incombination with an activator form metallocene-type catalyst systemscapable of polymerizing various olefin(s), alone or in combination withother olefin(s). The development of these and other metallocene-typecatalyst compounds and catalyst systems are described in U.S. Pat. Nos.5,017,714, 5,055,438, 5,096,867, 5,198,401, 5,229,478, 5,264,405,5,278,119, 5,324,800, 5,384,299, 5,408,017, 5,491,207 and 5,621,126 allof which are herein fully incorporated by reference.

It is well known in the art, although not fully understood, that wherethe transition metal of these metallocene-type catalyst compounds ishafnium, often referred to as a “hafnocene”, hafnocene catalyst systemsgenerally, among other characteristics, perform relatively poorly incomparison to their titanium, especially their zirconium equivalents,often referred to as “zirconocenes”. Although hafnocenes will typicallypolymerize polymers having higher molecular weights than theirzirconocene equivalents under similar polymerization conditions, theiroverall poor activity make them inferior polymerization catalysts.European patent EP 0 284 707 B1 granted Aug. 30, 1995, which is fullyincorporated herein by reference, describes a process for polymerizingolefins using a catalyst system, in liquid form, containing a chiral,sterorigid bridged hafnium metallocene catalyst compound and an aluminumcompound.

Thus, it would be highly advantageous to have a hafnium metallocene-typecatalyst system capable of polymerizing olefin(s) with improved catalystperformance.

SUMMARY OF THE INVENTION

In an embodiment, this invention relates to an ethylene copolymer havinga polymodal CD, wherein under temperature rising elution fractionation(TREF) analysis the ethylene copolymer evidences at least two peaks.

In another embodiment, this invention relates to an ethylene copolymerhaving a polymodal CD, wherein under temperature rising elutionfractionation (TREF) analysis the ethylene copolymer evidences at leasttwo peaks, and wherein the ethylene copolymer is produced in a singlereactor.

In still another embodiment, this invention relates to an ethylenecopolymer having a polymodal CD, wherein the ethylene copolymer isproduced in a single reactor; wherein under temperature rising elutionfractionation (TREF) analysis the ethylene copolymer evidences at leasttwo peaks; wherein the ethylene copolymer has an Mw/Mn of from about 2.5to about 7; wherein the ethylene copolymer has a density of from 0.905to 0.95 g/cc; wherein the ethylene copolymer exhibits a low-temperaturepeak position at about 65° C. under temperature rising elutionfractionation (TREF) analysis; wherein the ethylene copolymer exhibits apeak separation between the low-temperature and high-temperature peaksof a minimum of about 20° C. and a maximum of about 35° C. undertemperature rising elution fractionation (TREF) analysis; wherein theethylene copolymer exhibits low-temperature peak ranges from about 30mole % and the high-temperature peak is about 70 mole % undertemperature rising elution fractionation (TREF) analysis; and whereinthe ethylene copolymer comprises about 0.01 ppm to about 2 ppm hafnium.

DETAILED DESCRIPTION OF INVENTION Introduction

The invention is directed toward a hafnium transition metalmetallocene-type catalyst system for polymerizing one or more olefin(s).It has been surprisingly discovered that by properly substituting thecyclopentadienyl derived ligand or moiety of a hafnocene results in animproved catalyst system. Unexpectedly where the substituent on thebulky ligand or moiety is a substituent having 3 or more non-hydrogenatoms, preferably 3 or more carbon atoms, preferably an alkylsubstituent, for example n-propyl or n-butyl, the catalyst activity ofthe hafnocene metallocene-type catalyst system is substantiallyimproved. Along with a sufficiently commercially acceptable activity,the hafnocene catalyst systems of the invention produces polymers havinghigher molecular weights in comparison to its zirconocene equivalents atthe same or similar polymerization conditions. It was surprising thatthe substituted hafnocene of the invention will tend to produce lowerdensity polymer products than its zirconocene equivalent atsubstantially the same molecular weight.

Catalyst Components and Catalyst Systems

Preferred metallocene catalysts of the invention, for example, aretypically those bulky ligand transition metal complexes described byformula (I):{[(LP)_(m)M(A^(q))_(n)]^(+k)}_(h)[B′^(−j)]_(i)where L is a substituted bulky ligand bonded to M, p is the anioniccharge of L and m is the number of L ligands and m is 1, 2 or 3; atleast one L is substituted with at least one substituent having 3 ormore non-hydrogen atoms, preferably having 3 or more carbon atoms orsilicon atoms or combination thereof; A is a ligand bonded to M andcapable of inserting an olefin between the M-A bond, q is the anioniccharge of A and n is the number of A ligands and n is 1, 2, 3 or 4, M isa transition metal of which 95 mole % or greater is hafnium (Hf),preferably greater than 97 mole % Hf, more preferably greater than 98mole % Hf, and most preferably in the range of greater than 99 mole % Hfto less than 100 mole % Hf, and (p×m)+(q×n)+k corresponds to the formaloxidation state of the metal center; where k is the charge on the cationand k is 1, 2, 3 or 4, and B′ is a chemically stable, non-nucleophilicanionic complex, preferably having a molecular diameter of 4 Å orgreater and j is the anionic charge on B′, h is the number of cations ofcharge k, and i the number of anions of charge j such that h×k=j×i.

Any two L and/or A ligands may be bridged to each other and/orunbridged. The catalyst compound may be full-sandwich compounds havingtwo or more ligands L, which include cyclopentadienyl derived ligands orsubstituted cyclopentadienyl derived ligands, or half-sandwich compoundshaving one ligand L, which is a cyclopentadienyl derived ligand orheteroatom substituted cyclopentadienyl derived ligand or hydrocarbylsubstituted cyclopentadienyl derived ligand or moiety such as an indenylligand, a benzindenyl ligand or a fluorenyl ligand and the likeincluding hydrogenated versions thereof or any other ligand capable ofη-5 bonding to the transition metal atom. One or more of these bulkyligands is π-bonded to the transition metal atom. At least one L issubstituted with at least one substituent having 3 or more non-hydrogenatoms, preferably having 3 or more carbon atoms or 3 or morenon-hydrogen atoms of which at least one is a silicon atom; in addition,L can be substituted with a combination of additional substituents,which can be the same or different. Non-limiting examples ofnon-hydrogen atoms include silicon, germanium, tin, oxygen, nitrogen orcarbon and combinations thereof. Non-limiting examples of additionalsubstituents include hydrogen or a linear, branched or cyclic alkyl,alkenyl or aryl radical or combination thereof having from 1 to 30carbon atoms. The at least one substituent or the additionalsubstituents can also be substituted with hydrogen or a linear, branchedor cyclic alkyl, alkenyl or aryl radical having from 1 to 30 carbonatoms or non-hydrogen atoms. L may also be other types of bulky ligandsincluding but not limited to bulky amides, phosphides, alkoxides,aryloxides, imides, carbolides, borollides, porphyrins, phthalocyanines,corrins and other polyazomacrocycles. Other ligands may be bonded to thehafnium transition metal, such as a leaving group, such as—but notlimited to weak bases—such as amines, phosphines, ether and the like. Inaddition to the transition metal, these ligands may be optionally bondedto A or L. Non-limiting examples of catalyst components and catalystsystems are discussed, in for example, U.S. Pat. Nos. 4,530,914,4,871,705, 4,937,299, 5,124,418, 5,017,714, 5,120,867, 5,210,352,5,278,264, 5,278,119, 5,304,614, 5,324,800, 5,347,025, 5,350,723,5,391,790, 5,391,789, 5,399,636, 5,539,124, 5,455,366, 5,534,473,5,684,098 and 5,693,730; all of which are herein fully incorporated byreference. Also, the disclosures of European publications EP-A-0 591756, EP-A-0 520 732, EP-A-0 420 436, EP-B1 0 485 822, EP-B1 0 485 823and EP-A2-0 743 324 and PCT publications WO 91/04257, WO 92/00333, WO93/08221, WO 93/08199, WO 94/01471, WO 96/20233, WO 97/15582 and WO97/19959 are all herein fully incorporated by reference.

In one embodiment, the activated catalyst of the invention is formedfrom a hafnocene catalyst compound represented by the general formula(II):(LP)_(m)M(A^(q))_(n)(E^(r))_(o)where L is a bulky ligand substituted with at least one substituenthaving 3 or more non-hydrogen atoms, preferably 3 or more carbon atoms,preferably an alkyl substituent having 3 or more carbon atoms, even morepreferably a linear alkyl substituent having 3 or more carbon atoms, Mis Hf, A, and p, m, q and n are as defined above and E is an anionicleaving group such as but not limited to hydrocarbyl, hydride, halide orcombination thereof or any other anionic ligands; r is the anioniccharge of E and o is the number of E ligands and o is 1, 2, 3 or 4 suchthat (p×m)+(q×n)+(r×o) is equal to the formal oxidation state of themetal center; and an aluminum alkyl, alumoxane, modified alumoxane orany other oxy-containing organometallic compound or non-coordinatingionic activators, or a combination thereof.

In one embodiment of the invention the substituted hafnocene catalystcompound of the invention includes monocyclopentadienyl-heteroatomligand containing hafnium transition metal metallocene-type compounds.This metallocene-type compound is activated by either an alumoxane,modified alumoxane, a non-coordinating ionic activator, a Lewis acid ora combination thereof to form an active polymerization catalyst system.These types of catalyst systems are described in, for example, PCTpublication WO 92/00333, WO 94/07928, WO 91/04257, WO 94/03506,WO96/00244 and WO 97/15602 and U.S. Pat. Nos. 5,057,475, 5,096,867,5,055,438, 5,198,401, 5,227,440 and 5,264,405 and European publicationEP-A-0 420 436, all of which are herein fully incorporated by reference.Additionally it is within the scope of this invention that themetallocene catalysts and catalyst systems may be those described inU.S. Pat. Nos. 5,064,802, 5,145,819, 5,149,819, 5,243,001, 5,239,022,5,276,208, 5,296,434, 5,321,106, 5,329,031, 5,304,614 and 5,677,401, andPCT publications WO 93/08221, WO 93/08199 and WO 95/07140 and Europeanpublications EP-A-0 578 838 and EP-A-0 638 595 all of which are hereinfully incorporated by reference.

In another embodiment, the catalyst component is represented by theformula (III):(C₅H_(5-d-f)R″_(d))_(e)R′″_(f)MQ_(g-e)wherein M is a Hf transition metal, (C₅H_(5-d-f)R″_(d)) is anunsubstituted or substituted cyclopentadienyl ligand bonded to M,wherein at least one (C₅H_(5-d-f)R″_(d)) has at least one R″ that is analkyl substituent having 3 or more carbon atoms, each additional R″,which can be the same or different is hydrogen or a substituted orunsubstituted hydrocarbyl having from 1 to 30 carbon atoms orcombinations thereof or two or more carbon atoms are joined together toform a part of a substituted or unsubstituted ring or ring system having4 to 30 carbon atoms, R′″ is one or more or a combination of carbon,germanium, silicon, phosphorous or nitrogen atoms containing radicalbridging two (C₅H_(5-d-f)R″_(d)) rings, or bridging one(C₅H_(5-d-f)R″_(d)) ring to M; each Q which can be the same or differentis a hydride, substituted or unsubstituted hydrocarbyl having from 1 to30 carbon atoms, halogen, alkoxides, aryloxides, amides, phosphides orany other univalent anionic ligand or combination thereof; also, two Q'stogether form an alkylidene ligand or cyclometallated hydrocarbyl ligandor other divalent anionic chelating ligand, where g is an integercorresponding to the formal oxidation state of M, d is 0, 1, 2, 3, 4 or5, f is 0 or 1 and e is 1, 2 or 3.

In another preferred embodiment of this invention the catalyst componentis represented by the formula (IV):

wherein M is Hf; (C₅H_(5-y-x)R_(x)) is a cyclopentadienyl ring which issubstituted with from at least one to 5 substituent groups R, “x” is 1,2, 3, 4 or 5 denoting the degree of substitution, and at least one R isa non-hydrogen atom, preferably R is at least 3 carbon atoms or siliconatoms or a combination thereof, more preferably R is an alkyl having 3or more carbon atoms, for example n-propyl or n-butyl, and eachadditional substituent group R is, independently, a radical selectedfrom a group consisting of C₁-C₂₀ hydrocarbyl radicals, substitutedC₁-C₂₀ hydrocarbyl radicals wherein one or more hydrogen atoms isreplaced by a halogen atom, C₁-C₂₀ hydrocarbyl-substituted metalloidradicals wherein the metalloid is selected from the Group 14 of thePeriodic Table of Elements, and halogen radicals or (C₅H_(5-y-x)R_(x))is a cyclopentadienyl ring in which two adjacent R-groups are joinedforming C₄-C₂₀ ring to give a saturated or unsaturated polycycliccyclopentadienyl ligand such as indenyl, tetrahydroindenyl, fluorenyl oroctahydrofluorenyl;

(JR′_(z-1-y)) is a heteroatom ligand in which J is an element with acoordination number of three from Group 15 or an element with acoordination number of two from Group 16 of the Periodic Table ofElements, preferably nitrogen, phosphorus, oxygen or sulfur withnitrogen being preferred, and each R′ is, independently a radicalselected from a group consisting of C₁-C₂₀ hydrocarbyl radicals whereinone or more hydrogen atoms is replaced by a halogen atom, y is 0 or 1,and “z” is the coordination number of the element J;

each Q is, independently any univalent anionic ligand such as halogen,hydride, or substituted or unsubstituted C₁-C₃₀ hydrocarbyl, alkoxide,aryloxide, amide or phosphide, provided that two Q may be an alkylidene,a cyclometallated hydrocarbyl or any other divalent anionic chelatingligand;

A is a covalent bridging group containing a Group 15 or 14 element suchas, but not limited to, a dialkyl, alkylaryl or diaryl silicon orgermanium radical, alkyl or aryl phosphine or amine radical, or ahydrocarbyl radical such as methylene, ethylene and the like;

L′ is a Lewis base such as diethylether, tetraethylammonium chloride,tetrahydrofuran, dimethylaniline, aniline, trimethylphosphine,n-butylamine, and the like; and w is a number from 0 to 3. Additionally,L′ may be bonded to any of R, R′ or Q.

In one embodiment of the bulky ligand hafnium transition metalmetallocene-type catalyst compounds described above, at least one bulkyligand is substituted with a substituent having 3 or more carbon atoms,preferably 3 to 20 carbon atoms, more preferably 3 to 10 and mostpreferably 3 to 5 carbon atoms. In another preferred embodiment, thehafnium transition metal metallocene-type catalyst system has two bulkyligands that are each substituted with a linear or branched, preferablylinear, alkyl having 3 or more carbon atoms, preferably 3 to 10 carbonatoms, most preferably 3 to 5 carbon atoms, where at least one bulkyligand is a cyclopentadienyl derived ligand, preferably acyclopentadienyl ring. In a preferred embodiment the bulky ligands ofthe hafnium transition metal metallocene are both cyclopentadienyl ringsat least one of which is substituted with one or more branched or linearalkyls having 3 or more carbon atoms, preferably both cyclopentadienylrings are substituted with at least one n-propyl, isopropyl, n-butyl,isobutyl, n-pentyl, or combination thereof. In a more preferredembodiment the hafnium transition metal metallocene-type catalystcompound has two bulky ligands that are each substituted with n-propyl,n-butyl or n-pentyl or combination thereof, in the same or differentpositions, preferably in the same position on the bulky ligands.

In another preferred embodiment, the hafnium transition metalmetallocene-type catalyst system has two bulky ligands that are eachsubstituted with a linear or branched, preferably linear, silyl having 3or more non-hydrogen atoms, preferably 3 to 10 non-hydrogen atoms, mostpreferably 3 to 5 non-hydrogen atoms, where at least one bulky ligand isa cyclopentadienyl derived ligand, preferably a cyclopentadienyl ring.In a preferred embodiment the bulky ligands of the hafnium transitionmetal metallocene are both cyclopentadienyl rings at least one of whichis substituted with one or more branched or linear silylalkyls having 3or more non-hydrogen atoms. In one embodiment, the substituent has atleast 3 or more non-hydrogen atoms of which at least one is a siliconatom, for example trimethyl silyl alkyl, tributyl silyl alkyl ortripropyl silyl alkyl or even cyclopropyl silyl. Other non-hydrogensubstituent atoms include oxygen and/or nitrogen.

It is contemplated that the substituted bulky ligands of the hafniumtransition metal metallocene-type catalyst compound of the invention areasymmetrically substituted in terms of additional substituents or typesof substituents, and/or unbalanced in terms of the number of additionalsubstituents on the bulky ligands.

Non-limiting examples of hafnocenes of the invention includebis(n-propyl cyclopentadienyl) hafnium dichloride, dimethyl ordihydride, bis(n-butyl cyclopentadienyl) hafnium dichloride or dimethyl,bis(n-pentyl cyclopentadienyl) hafnium dichloride or dimethyl, (n-propylcyclopentadienyl)(n-butyl cyclopentadienyl) hafnium dichloride ordimethyl, bis[(2-trimethylsilyl-ethyl)cyclopentadienyl]hafniumdichloride or dimethyl, bis(trimethylsilyl cyclopentadienyl) hafniumdichloride or dimethyl or dihydride, bis(2-n-propyl indenyl) hafniumdichloride or dimethyl, bis(2-n-butyl indenyl) hafnium dichloride ordimethyl, dimethylsilyl bis(n-propyl cyclopentadienyl) hafniumdichloride or dimethyl, dimethylsilyl bis(n-butyl cyclopentadienyl)hafnium dichloride or dimethyl, bis(9-n-propyl fluorenyl) hafniumdichloride or dimethyl, bis(9-n-butyl fluorenyl) hafnium dichloride ordimethyl, (9-n propyl fluorenyl)(2-n-propyl indenyl) hafnium dichlorideor dimethyl, bis(1,2-n-propyl, methyl cyclopentadienyl) hafniumdichloride or dimethyl, (n-propyl cyclopentadienyl)(1,3-n-propyl,n-butyl cyclopentadienyl) hafnium dichloride or dimethyl and the like.

In one preferred embodiment the hafnocenes of the invention areunbridged mono- and bis-hafnocenes where a structural bridge is notrequired for stereorigidty. It is also contemplated that in oneembodiment, the hafnocenes of the invention include their structural oroptical isomers and mixtures thereof.

For the purposes of this patent specification and appended claims, theterm “activator” is defined to be any compound or component which canactivate a bulky ligand transition metal metallocene-type catalystcompound as described above, for example, a Lewis acid or anon-coordinating ionic activator or ionizing activator or any othercompound that can convert a neutral metallocene catalyst component to ametallocene cation. It is within the scope of this invention to usealumoxane or modified alumoxane as an activator, and/or to also useionizing activators, neutral or ionic, such as tri (n-butyl) ammoniumtetrakis(pentafluorophenyl) boron or a trisperfluorophenyl boronmetalloid precursor which ionize the neutral metallocene compound.

There are a variety of methods for preparing alumoxane and modifiedalumoxanes, non-limiting examples of which are described in U.S. Pat.Nos. 4,665,208, 4,952,540, 5,091,352, 5,206,199, 5,204,419, 4,874,734,4,924,018, 4,908,463, 4,968,827, 5,308,815, 5,329,032, 5,248,801,5,235,081, 5,157,137, 5,103,031, 5,391,793, 5,391,529, 5,693,838 andEuropean publications EP-A-0 561 476, EP-B1-0 279 586 and EP-A-0594-218, and PCT publication WO 94/10180, all of which are herein fullyincorporated by reference.

Ionizing compounds may contain an active proton, or some other cationassociated with but not coordinated or only loosely coordinated to theremaining ion of the ionizing compound. Such compounds and the like aredescribed in European publications EP-A-0 570 982, EP-A-0 520 732,EP-A-0 495 375, EP-A-0 426 637, EP-A-500 944, EP-A-0 277 003 and EP-A-0277 004, and U.S. Pat. Nos. 5,153,157, 5,198,401, 5,066,741, 5,206,197,5,241,025, 5,387,568, 5,384,299 and 5,502,124 and U.S. patentapplication Ser. No. 08/285,380, filed Aug. 3, 1994, all of which areherein fully incorporated by reference. Combinations of activators arealso contemplated by the invention, for example, alumoxanes and ionizingactivators in combinations, see for example, PCT publications WO94/07928 and WO 95/14044 and U.S. Pat. Nos. 5,153,157 and 5,453,410 allof which are herein fully incorporated by reference.

In an embodiment of the invention two or more bulky ligand hafniumtransition metal metallocene-type catalyst compounds as described abovecan be combined to form a catalyst system useful in the invention. Forexample, those mixed catalysts described in U.S. Pat. Nos. 5,281,679,5,359,015 and 5,470,811, all of which are herein fully incorporatedherein reference. In another embodiment of the catalyst system of theinvention combinations of one or more of catalyst components of theformulas (III) and/or (IV) are contemplated.

In one embodiment, metallocene catalyst components can be combined toform the blend compositions as described in PCT publication WO 90/03414published Apr. 5, 1990, herein fully incorporated by reference. In yetanother embodiment of the invention mixed metallocenes as described inU.S. Pat. Nos. 4,937,299 and 4,935,474, both are herein fullyincorporated herein by reference, can be used to produce polymers havinga broad molecular weight distribution and/or a multimodal molecularweight distribution. As a particular aspect of this embodiment of theinvention the hafnium metallocene is a bis(n-propylcyclopentadienyl)hafnium dichloride or dimethyl which comprises at least 95 mole % of thetransition metal catalyst component and the balance is abis(n-propylcyclopentadienyl) zirconium dichloride or dimethyl whichcomprises at least 0.1 mole % of the transition metal catalystcomponent.

In one embodiment, an ethylene-alpha-olefin copolymer having a densityin the range of from about 0.87 g/cc to about 0.940 g/cc is produced bythe catalyst system of the invention. In one preferred embodiment, theethylene-alpha-olefin copolymers of the invention have a density of atleast about 0.910 g/cc. These copolymers produced by a catalyst systemof this invention are especially well suited for making films having anew balance of film properties as compared to films heretofore producedfrom commercially available metallocene produced resins such as DowELITE™ and/or Exxon EXCEED™ resins of similar densities and melt index(MI) values.

In another embodiment of the invention at least one metallocene catalystof the invention can be combined with a non-metallocene or traditionalZiegler-Natta catalyst or catalyst system, or chromium based catalystsor catalyst systems, non-limiting examples are described in U.S. Pat.Nos. 4,159,965, 4,325,837, 4,701,432, 5,124,418, 5,077,255, 5,183,867,5,391,660, 5,395,810 and 5,691,264, all of which are herein fullyincorporated by reference.

It is within the scope of this invention that Ni²⁺ and Pd²⁺ complexesdescribed in the articles by Johnson, et al., “New Pd(II)— and Ni(II)—Based Catalysts for Polymerization of Ethylene and α-Olefins”, J. Am.Chem. Soc. 1995, 117, 6414-6415 and “Copolymerization of Ethylene andPropylene with Functionalized Vinyl Monomers by Palladium(II)Catalysts”, J. Am. Chem. Soc., 1996, 118, 267-268, and WO 96/23010published Aug. 1, 1996, which are all herein fully incorporated byreference, can be used as catalysts in combination with the hafnocenesof the invention. These complexes can be either dialkyl ether adducts,or alkylated reaction products of the described dihalide complexes thatcan be activated to a cationic state by the activators of thisinvention. It is also within the scope of the process of this inventionthat the above described complexes can be combined with one or more ofthe catalyst compounds represented by formula (III) and (IV), with oneor more activators, and with one or more of the support materials usingone of the support methods that are described below.

For purposes of this patent specification the terms “carrier” or“support” are interchangeable and can be any support material,preferably a porous support material, for example, talc, inorganicoxides, inorganic chlorides, and magnesium chloride, and resinoussupport materials such as polystyrene or polystyrene divinyl benzenepolyolefins or polymeric compounds or any other organic or inorganicsupport material and the like, or mixtures thereof.

The preferred support materials are inorganic oxide materials, whichinclude those of Groups 2, 3, 4, 5, 13 or 14 metal oxides. In apreferred embodiment, the catalyst support materials include silica,alumina, silica-alumina, and mixtures thereof. Other inorganic oxidesthat may be employed either alone or in combination with the silica,alumina or silica-alumina and magnesia, titania, zirconia, and the like.

It is preferred that the carrier of the catalyst of this invention has asurface area in the range of from about 10 to about 700 m²/g, porevolume in the range of from about 0.1 to about 4.0 cc/g and averageparticle size in the range of from about 10 to about 500 μm. Morepreferably, the surface area is in the range of from about 50 to about500 m²/g, pore volume of from about 0.5 to about 3.5 cc/g and averageparticle size of from about 20 to about 200 μm. Most preferably thesurface area range is from about 100 to about 400 m²/g, pore volume fromabout 0.8 to about 3.0 cc/g and average particle size is from about 20to about 100 μm. The average pore size of the carrier of the inventiontypically has pore size in the range of from 10 to 1000 Å, preferably 50to about 500 Å, and most preferably 75 to about 350 Å.

The catalyst system of the invention can be made and used in a varietyof different ways as described below. In one embodiment the catalyst isunsupported, preferably in liquid form such as described in U.S. Pat.Nos. 5,317,036 and 5,693,727 and European publication EP-A-0 593 083,all of which are herein incorporated by reference. In the preferredembodiment, the catalyst system of the invention is supported. Examplesof supporting the catalyst system used in the invention are described inU.S. Pat. Nos. 4,701,432, 4,808,561, 4,912,075, 4,925,821, 4,937,217,5,008,228, 5,238,892, 5,240,894, 5,332,706, 5,346,925, 5,422,325,5,466,649, 5,466,766, 5,468,702, 5,529,965, 5,554,704, 5,629,253,5,639,835, 5,625,015, 5,643,847 and 5,665,665 and U.S. application Ser.Nos. 271,598 filed Jul. 7, 1994 and 788,736 filed Jan. 23, 1997 and PCTpublications WO 95/32995, WO 95/14044, WO 96/06187 and WO 97/02297 allof which are herein fully incorporated by reference.

In another embodiment, the catalyst system of the invention contains apolymer bound ligand as described in U.S. Pat. No. 5,473,202 which isherein fully incorporated by reference. In one embodiment the catalystsystem of the invention is spray dried as described in U.S. Pat. No.5,648,310 which is fully incorporated herein by reference. In anembodiment the support of the invention is functionalized as describedin European publication EP-A-0 802 203 or at least one substituent orleaving group is selected as described in U.S. Pat. No. 5,688,880, bothof which are herein fully incorporated by reference.

In one embodiment of the process of the invention, olefin(s), preferablyC₂ to C₃₀ olefin(s) or alpha-olefin(s), preferably ethylene or propyleneor combinations thereof are prepolymerized in the presence of thecatalyst or catalyst system of the invention prior to the mainpolymerization. The prepolymerization can be carried out batchwise orcontinuously in gas, solution or slurry phase including at elevatedpressures. The prepolymerization can take place with any alpha-olefinmonomer or combination and/or in the presence of any molecular weightcontrolling agent such as hydrogen. For details on prepolymerization seeU.S. Pat. Nos. 4,923,833, 4,921,825 and 5,283,278 and Europeanpublication EP-B-0279 863 all of which are herein fully incorporated byreference.

In another embodiment of the invention, the supported catalyst system ofthe invention includes an antistatic agent or surface modifier, forexample, those described in U.S. Pat. No. 5,283,278 and PCT publicationWO 96/11960 which are herein fully incorporated by reference.Non-limiting examples of antistatic agents and surface modifiers includealcohol, thiol, silanol, diol, ester, ketone, aldehyde, acid, amine, andether compounds. Tertiary amines, ethoxylated amines, and polyethercompounds are preferred. The antistatic agent can be added at any stagein the formation of the supported catalyst system of the invention,however, it is preferred that it is added after the supported catalystsystem of the invention is formed, in either a slurry or dried state.

A preferred method for producing the catalyst of the invention isdescribed below and can be found in U.S. Application Serial Nos.265,533, filed Jun. 24, 1994 and 265,532, filed Jun. 24, 1994 and PCTpublications WO 96/00245 and WO 96/00243 both published Jan. 4, 1996,all of which are herein fully incorporated by reference. In a preferredembodiment, the metallocene-type catalyst component is slurried in aliquid to form a metallocene solution and a separate solution is formedcontaining an activator and a liquid. The liquid can be any compatiblesolvent or other liquid capable of forming a solution or the like withat least one metallocene catalyst component and/or at least oneactivator. In the preferred embodiment the liquid is a cyclic aliphaticor aromatic hydrocarbon, most preferably toluene. The metallocene andactivator solutions are mixed together and added to a porous support orthe porous support is added to the solutions such that the total volumeof the metallocene solution and the activator solution or themetallocene and activator solution is less than four times the porevolume of the porous support, more preferably less than three times,even more preferably less than two times; preferred ranges being from1.1 times to 3.5 times range and most preferably in the 1.2 to 3 timesrange.

Procedures for measuring the total pore volume of a porous support arewell known in the art. Details of one of these procedures is discussedin Volume 1, Experimental Methods in Catalytic Research (Academic Press,1968) (specifically see pages 67-96). This preferred procedure involvesthe use of a classical BET apparatus for nitrogen absorption. Anothermethod well know in the art is described in Innes, Total Porosity andParticle Density of Fluid Catalysts By Liquid Titration, Vol. 28, No. 3,Analytical Chemistry 332-334 (March, 1956).

The mole ratio of the metal of the activator component to the transitionmetal of the metallocene component is in the range of ratios between0.3:1 to 1000:1, preferably 20:1 to 800:1, and most preferably 50:1 to500:1. Where the activator is an aluminum-free ionizing activator suchas those based on the anion tetrakis(pentafluorophenyl)boron, the moleratio of the metal of the activator component to the transition metalcomponent is preferably in the range of ratios between 0.3:1 to 3:1.

In another embodiment the catalyst loading in millimoles (mmoles) ofmetallocene to weight of support catalyst in grams (g) is in the rangeof from about 0.001 to about 2.0 mmoles of metallocene per g of supportmaterial, preferably from about 0.005 to about 1.0, more preferably fromabout 0.005 to 0.5 and most preferably from about 0.01 to 0.05.

In one embodiment, the catalyst of the invention has a catalystproductivity of greater than 1000 grams of polymer per gram of themetallocene catalyst, preferably greater than 1400 grams of polymer pergram of metallocene catalyst, more preferably greater than 1800 grams ofpolymer per gram of metallocene catalyst, even more preferably greaterthan 2000 grams of polymer per gram of metallocene catalyst, and mostpreferably greater than 2500 grams of polymer per gram of metallocenecatalyst.

Polymerization Process of the Invention

The substituted bulky ligand hafnium transition metal metallocene-typecatalyst compounds and catalyst systems of this invention are suited forthe polymerization of monomers, and optionally one or more comonomers,in any polymerization process, solution phase, gas phase or slurryphase, most preferably a gas or slurry phase process is used.

In an embodiment, this invention is directed toward the solution, slurryor gas phase polymerization or copolymerization reactions involving thepolymerization of one or more of the monomers having from 2 to 30 carbonatoms, preferably 2-12 carbon atoms, and more preferably 2 to 8 carbonatoms. The invention is particularly well suited to the copolymerizationreactions involving the polymerization of one or more of the monomers,for example alpha-olefin monomers of ethylene, propylene, butene-1,pentene-1,4-methyl-pentene-1, hexene-1, octene-1, decene-1, and cyclicolefins such as cyclopentene, and styrene or a combination thereof.Other monomers can include polar vinyl monomers, diolefins such asdienes, polyenes, norbornene, norbornadiene, acetylene and aldehydemonomers. Preferably a copolymer of ethylene or propylene is produced.Preferably the comonomer is an alpha-olefin having from 3 to 15 carbonatoms, preferably 4 to 12 carbon atoms and most preferably 4 to 8 carbonatoms. In another embodiment ethylene or propylene is polymerized withat least two different comonomers to form a terpolymer and the like, thepreferred comonomers are a combination of alpha-olefin monomers having 3to 10 carbon atoms, more preferably 4 to 8 carbon atoms.

In another embodiment ethylene or propylene is polymerized with at leasttwo different comonomers to form a terpolymer and the like, thepreferred comonomers are a combination of alpha-olefin monomers having 3to 10 carbon atoms, more preferably 3 to 8 carbon atoms, optionally withat least one diene monomer. The preferred terpolymers include thecombinations such as ethylene/butene-1/hexene-1,ethylene/propylene/butene-1, propylene/ethylene/butene-1,propylene/ethylene/hexene-1, ethylene/propylene/norbornadiene and thelike.

In the most preferred embodiment the process of the invention relates tothe polymerization of ethylene and at least one comonomer having from 4to 8 carbon atoms. Particularly, the comonomers arebutene-1,4-methyl-pentene-1, hexene-1 and octene-1, the most preferredbeing hexene-1.

Typically in a gas phase polymerization process a continuous cycle isemployed where in one part of the cycle of a reactor, a cycling gasstream, otherwise known as a recycle stream or fluidizing medium, isheated in the reactor by the heat of polymerization. This heat isremoved in another part of the cycle by a cooling system external to thereactor. (See for example U.S. Pat. Nos. 4,543,399, 4,588,790,5,028,670, 5,317,036, 5,352,749, 5,405,922, 5,436,304, 5,453,471,5,462,999, 5,616,661 and 5,668,228 all of which are fully incorporatedherein by reference.)

Generally, in a gas fluidized bed process for producing polymers, agaseous stream containing one or more monomers is continuously cycledthrough a fluidized bed in the presence of a catalyst under reactiveconditions. The gaseous stream is withdrawn from the fluidized bed andrecycled back into the reactor. Simultaneously, polymer product iswithdrawn from the reactor and fresh monomer is added to replace thepolymerized monomer. The reactor pressure may vary from about 100 psig(680 kPag) to about 500 psig (3448 kPag), preferably in the range offrom about 200 psig (1379 kPag) to about 400 psig (2759 kPag), morepreferably in the range of from about 250 psig (1724 kPag) to about 350psig (2414 kPag). The reactor temperature may vary between about 60° C.and about 120° C., preferably about 60° C. to about 115° C., and morepreferably in the range of from about 70° C. to 110° C., and mostpreferably in the range of from about 70° C. to 95° C. The settled bulkdensity for the polymers produced by the process of invention are in therange of from about 10 to 35 lb/ft³ (160 to 561 kg/m³), preferably fromabout 12 to 35 lb/ft³ (193 to 561 kg/m³), more preferably from about 14to 32 lb/ft³ (224 to 513 kg/m³), and most preferably from about 15 to 30lb/ft³ (240 to 481 kg/m³).

Other gas phase processes contemplated by the process of the inventioninclude those described in U.S. Pat. Nos. 5,627,242, 5,665,818 and5,677,375, and European publications EP-A-0 794 200, EP-A-0 802 202 andEP-B-634 421 all of which are herein fully incorporated by reference.

A preferred process of the invention is where the process, preferably aslurry or gas phase process, most preferably a gas phase process, isoperated in the absence of or essentially free of any scavengers, suchas triethylaluminum, trimethylaluminum, tri-isobutylaluminum andtri-n-hexylaluminum and diethyl aluminum chloride and the like. Thispreferred process is described in PCT publication WO 96/08520, which isherein fully incorporated by reference.

A slurry polymerization process generally uses pressures in the range ofabout 1 to about 50 atmospheres and even greater and temperatures in therange of 0° C. to about 200° C. In a slurry polymerization, a suspensionof solid, particulate polymer is formed in a liquid polymerizationmedium to which ethylene and comonomers and often hydrogen along withcatalyst are added. The liquid employed in the polymerization medium canbe alkane or cycloalkane, or an aromatic hydrocarbon such as toluene,ethylbenzene or xylene. The medium employed should be liquid under theconditions of polymerization and relatively inert. Preferably, hexane orisobutane medium is employed.

In one embodiment a preferred polymerization technique of the inventionis referred to as a particle form, or slurry process where thetemperature is kept below the temperature at which the polymer goes intosolution. Such technique is well known in the art, see for instance U.S.Pat. No. 3,248,179 which is fully incorporated herein by reference. Thepreferred temperature in the particle form process is within the rangeof about 185° F. (85° C.) to about 230° F. (110° C.). Two preferredpolymerization methods for the slurry process are those employing a loopreactor and those utilizing a plurality of stirred reactors in series,parallel, or combinations thereof. Non-limiting examples of slurryprocesses include continuous loop or stirred tank processes. Also, otherexamples of slurry processes are described in U.S. Pat. No. 4,613,484,which is herein fully incorporated by reference.

It is also contemplated in an embodiment of the invention, that theprocess is a multistage polymerization process where one reactor isoperating in slurry phase that feeds into a reactor operating in a gasphase as described in U.S. Pat. No. 5,684,097, which is fullyincorporated herein by reference.

In one embodiment the reactor utilized in the present invention iscapable of producing greater than 500 lbs/hr (227 Kg/hr) to about200,000 lbs/hr (90,900 Kg/hr) or higher of polymer, preferably greaterthan 1000 lbs/hr (455 Kg/hr), more preferably greater than 10,000 lbs/hr(4540 Kg/hr), even more preferably greater than 25,000 lbs/hr (11,300Kg/hr), still more preferably greater than 35,000 lbs/hr (15,900 Kg/hr),still even more preferably greater than 50,000 lbs/hr (22,700 Kg/hr) andmost preferably greater than 65,000 lbs/hr (29,000 Kg/hr) to greaterthan 100,000 lbs/hr (45,500 Kg/hr).

The productivity of the catalyst or catalyst system is influenced by themain monomer partial pressure. The preferred mole percent of the mainmonomer, ethylene or propylene, preferably ethylene is from about 25 to90 mole percent and the monomer partial pressure is in the range of fromabout 75 psia (517 kPa) to about 300 psia (2069 kPa), which are typicalconditions in a gas phase polymerization process.

In another embodiment of the invention where the hafnocene of theinvention is in particular an unbridged metallocene-type catalyst, theprocess of the invention is capable of producing a polymer producthaving a melt index of less than 0.1 dg/min without the addition ofhydrogen to the process.

Polymer Product of the Invention

The polymers produced by this invention can be used in a wide variety ofproducts and end-use applications. The polymers typically have a densityin the range of from 0.86 g/cc to 0.97 g/cc, preferably in the range offrom 0.88 g/cc to 0.965 g/cc, more preferably in the range of from 0.900g/cc to 0.96 g/cc, even more preferably in the range of from 0.905 g/ccto 0.95 g/cc, yet even more preferably in the range from 0.910 g/cc to0.940 g/cc, and most preferably greater than 0.910 g/cc, preferablygreater than 0.915 g/cc. The polymers of the invention typically have anarrow molecular weight distribution, a weight average molecular weightto number average molecular weight (M_(w)/M_(n)) of greater than 1.5 toabout 4, particularly greater than 2 to about 3, more preferably greaterthan about 2.2 to less than 3. Also, the polymers of the inventiontypically have a narrow composition distribution. In another embodiment,the polymers produced by the process of the invention, particularly in aslurry and gas phase process, contain less than 5 ppm hafnium, generallyless than 2 ppm hafnium, preferably less than 1.5 ppm hafnium, morepreferably less than 1 ppm hafnium. In an embodiment, the polymer of theinvention contains in the range of from about 0.01 ppm to about 2 ppmhafnium, preferably in the range of from about 0.01 ppm to about 1.5 ppmhafnium, more preferably in the range of from about 0.01 ppm to 1 orless ppm hafnium.

Polymers produced by the process of the invention are useful in suchforming operations as film, sheet, and fiber extrusion and co-extrusionas well as blow molding, injection molding and rotary molding. Filmsinclude blown or cast films formed by coextrusion or by laminationuseful as shrink film, cling film, stretch film, sealing films, orientedfilms, snack packaging, heavy duty bags, grocery sacks, baked and frozenfood packaging, medical packaging, industrial liners, membranes, etc. infood-contact and non-food contact applications. Fibers include meltspinning, solution spinning and melt blown fiber operations for use inwoven or non-woven form to make filters, diaper fabrics, medicalgarments, geotextiles, etc. Extruded articles include medical tubing,wire and cable coatings, geomembranes, and pond liners. Molded articlesinclude single and multi-layered constructions in the form of bottles,tanks, large hollow articles, rigid food containers and toys, etc.

In one embodiment of this invention the polymerization product is alinear low-density polyethylene (LLDPE) resin produced by polymerizationof ethylene and an alpha-olefin comonomer having from 3 to 20 carbonatoms, preferably hexene-1. The ethylene copolymers of the inventionhave from 1 to about 5 mole % alpha-olefin comonomer incorporated intothe copolymer. For LLDPE resins of the invention, the ethylene copolymertypically has a polymer density greater than or equal 0.910 g/cc,preferably greater than or equal to 0.915 g/cc, and a polymer weightaverage molecular weight ≧25,000. In a preferred embodiment, theethylene alpha-olefin copolymers of the invention are produced with acatalyst system having a hafnocene component of at least 95 mole % ofall transition metal compound component and the balance is a zirconoceneof comparable ligand structure that comprises at least about 0.1 mole %of the transition metal compound component of the catalyst. In anotherembodiment of this invention, the resins, particularly the LLDPE resinsso produced by a catalyst system of this invention is thereafterconverted into a article of manufacture, especially a film. A catalystcomponent as above described may be produced from a HfCl₄ reagent forproduction of the transition metal compound catalyst component whicheither has at least from about 0.1 mole % up to about 5 mole % of aZrCl₄ contaminant, or otherwise ZrCl₄ is added to the HfCl₄ reagent inan amount sufficient to make up this mole % requirement for thetransition metal compound component of the overall catalyst system.

In one embodiment of this invention, a hafnium metallocene compound aspreviously described, but having a minor content of a zirconocenecompound of comparable structure is utilized as the transition metalcomponent for a catalyst system in supported form for the production ofthe ethylene copolymer of the invention, especially a linear low densitypolyethylene resin. Typically the minor amount of zirconium metalloceneis in the range of 0.1 to 4 mole % as is typically the concentration ofa zirconium tetrachloride contaminant in a hafnium tetrachloride reagentfrom which the transition metal component for the catalyst system ismade. If the zirconium component is present in an insufficient amount,then the content of this zirconium component in the hafnium reagent forcatalyst production may be increased by direct addition of the desiredquantity of zirconium tetrachloride.

Any of the known activators as previously described may be used toactivate the transition metal compound that is predominantly a hafnocenewith a small content of zirconocene to an active catalytic state.Although this catalyst system may be used in any mode for olefinpolymerization—solution, solvent, slurry, or gas phase—since slurry andgas phase polymerization are preferred modes for production of the LLDPEresins, preferably the catalysts is in supported form, preferably on asilica support.

The monomer supplied to the polymerization zone is regulated to providea ratio of ethylene to alpha-olefin comonomer in proportion so as toyield a polyethylene of comonomer content, as a bulk measurement,preferably of from about 0.5 to about 5.0 mole % comonomer, to yield inbulk a resin of density preferably of from about 0.95 g/cc to about0.915 g/cc. The reaction temperature, monomer residence time, andcatalyst system component quantities molecular weight control agent(such as H₂) are regulated so as to provide a resin, preferably a LLDPEresin of weight average molecular weight from about 25,000 to about150,000, a number average molecular weight from about 3500 to about60,000, preferably to about 50,000, so as to provide the resin,preferably a LLDPE resin, a molecular weight distribution value of fromabout 2.5 to about 7, preferably from about 3 to 7.

A ethylene copolymer so produced with the hafnium based catalyst system(having 0.1 to 4 mole % zirconium analog structure) in a single reactor,preferably a gas phase reactor, possessed unique molecularcharacteristics among which are a broadened molecular weightdistribution (MWD) and a polymodal CD. Such ethylene copolymers are moreeasily extruded into film products by cast or blown bubble filmprocessing techniques with lower motor load, higher throughput andreduced head pressure as compared to EXCEED™ resins of comparablecomonomer type and density. Such ethylene copolymers, particularly theLLDPE resins of the invention, have for a comparable MI a higher weightaverage molecular weight and a broader MWD than does an EXCEED™ resin.For cast film production with a resin of about 2.0 to about 5.0 MI, andpreferably about 3 MI, the LLDPE has a greater melt strength and higherbreak velocity than that of an EXCEED™ resin and the LLDPE cast film hasa new balance of stiffness and toughness and generally improved balanceof tear and dart properties. For a resin of about 0.5 to about 2.0 MI,and preferably of about MI=1.0, converted into film by a blown bubbletechnique, the LLDPE resin has, by comparison to a blown film producedfrom an EXCEED™ resin, a higher 1% secant modulus in the transversedirection and improved dart properties. In both cases the LLDPE resinhas a higher energy specific output (ESO) value by comparison to anEXCEED™ resin for conversion of it into a film.

Hence, because of the higher activity of the hafnocenes here described,it is now possible to practically produce the ethylene copolymers of theinvention, especially the LLDPE resins of the invention, in a single gasphase reactor as described above and such LLDPE resins are particularlywell suited to the processing into film articles by cast and blown filmprocedures.

Further characteristics of the LLDPE resins described above whichdistinguishes these LLDPE resins from EXCEED™ type resins is that undertemperature rising effluent elution fractionation (TREF) analysis theseLLDPE resins evidence two peaks whereas an EXCEED™ type resin evidencesbut a single peak. In the ethylene copolymers of the invention,particularly the LLDPEs of this invention, TREF analysis exhibits alow-temperature (low-T) peak position at 45-75° C., and preferably atabout 65° C.; a peak separation between the low-T and high-temperature(high-T) peaks of a minimum of about 20° C. and a maximum of about 35°C. with a preferred peak separation of about 25° C. Using a Gaussian fitto the TREF via multiple-peak method (a generic mathematical model)shows that the low-T peak which is also the low density fraction rangesfrom about 10 mole % to a maximum of about 90 mole % and in a preferredLLDPE resin the low low-T peak is preferably about 30 mole % and thehigh-T peak is about 70 mole %. For a LLDPE as above described withhexene as comonomer the total comonomer content may range from about 1to about 5 mole % and preferably is about 3 mole % (at which its ASTMdensity is about 0.918 g/cc). LLDPEs as above described with hexene inparticular as the comonomer will exhibit a weight average molecularweight of about 25,000 to 150,000 at corresponding MI values that rangebetween about 10 to about 0.1 MI, and preferably the weight averagemolecular weight ranges from about 80,000 to 110,000 within which rangethe melt index respectively ranges from a value of about 3 to about 1.For such LLDPE resins the melt index ratio (MIR) (I₂₁/I₂ as measured byASTM standard procedures) is greater than 15 to about 100, preferably inthe range of from 18 to 50, more preferably in the range of from about20 to less than about 40 and most preferably from about 23 to about 35;the molecular weight distribution (MWD) is at least about 2.5 and atmost 7, preferably from about 3 to 7; and the M_(z)/M_(w) ratio is atleast 2 and at most about 3.5 and preferably is about 2.8.

Cast films produced from such LLDPE resin resins having an MI of 2 to 4will have a 1% secant modulus greater than 14.5 kpsi film layer and lessthan 21 kpsi, a machine direction tear of greater than 100 g/mil andless than 600 g/mil, a transverse direction tear of greater than 100g/mil and less than 1000 g/mil, a 26″ dart value greater than 100 g/miland less than 1400 g/mil. Such cast film will also have a machinedirection tensile at break greater than 7 kpsi (48 kPa) and less than 11kpsi (76 kPa), a transverse direction tensile at break greater than 5kpsi (34 kPa) and less than 6.5 kpsi (45 kPa), a machine directionelongation at break greater than 325% and less than 600%, a transversedirection at break greater than 550% and less than 750%. Blown filmsproduced from such LLDPE resins having an MI of 0.5 to 2.0 will have a1% secant modulus greater than 26 kpsi (179 kPa) and less than 33 kpsi(227 kPa) and a 26″ dart value greater than 1200 g/mil.

EXAMPLES

In order to provide a better understanding of the present inventionincluding representative advantages thereof, the following examples areoffered.

The properties of the polymer were determined by the following testmethods:

Density is measured in accordance with ASTM-D-1238.

MWD, or polydispersity, is a well-known characteristic of polymers. MWDis generally described as the ratio of the weight average molecularweight (Mw) to the number average molecular weight (M_(n)). The ratio ofM_(w)/M_(n) can be measured by gel permeation chromatography techniques,or indirectly, by measuring the ratio (MIR) of 121 to 12 (melt index) asdescribed in ASTM D-1238-F and ASTM D-1238-E respectively.

In all the Examples below the methylalumoxane (MAO) is a 30 weightpercent MAO solution in toluene available from Albemarle Corporation,Baton Rouge, La., the Davison 948 silica is available from W.R. Grace,Davison Chemical Division, Baltimore, Md. and theN,N-bis(2-hydroxylethyl) octadecylamine is available as Kemamine AS-990from ICI Specialties, Wilmington, Del. The metallocene components of theexamples were prepared in accordance with procedures well known in theart.

Example 1 Preparation of Catalyst

A solution of methylalumoxane and metallocene was formed by adding 11cm³ of 30 wt-% MAO solution in toluene onto 0.202 g ofbis(n-propylcyclopentadienyl) hafnium dichloride in a vial. 40 cm³ offresh toluene was added, and the mixture stirred for 1 hour at 25° C.This pre-mixed solution of the MAO and the metallocene was then addedonto 10 g of Davison 948 silica dried to 600° C. The resulting slurrywas stirred for 1.5 hours at 25° C. The final catalyst was then dried tofree-flowing powder under vacuum at 65° C.

Polymerization

A sample of the dry catalyst formed in the above Example 1 was then usedin a polymerization process of ethylene/1-butene in a 2-liter semi-batchgas-phase reactor at 85° C. The pressure in the reactor, about 155 psig(1069 kPag), was held constant by continuously feeding 5 mol-% 1-butenein ethylene to compensate for any pressure changes due topolymerization. After 1 h (hour), the polymer formed was separated fromthe seed bed material and analyzed for the molecular properties shown inTable 1 below as Run 1 and 2.

Example 2 Preparation of Catalyst

A solution of methylalumoxane and metallocene was formed by adding 66.5cm³ of 30 wt-% MAO solution in toluene onto 1.21 g ofbis(n-propylcyclopentadienyl) hafnium dichloride in a vial. 50 cm³ offresh toluene was added, and the mixture stirred for 1.5 hours at 25° C.This pre-mixed solution of the MAO and the metallocene was then addedonto 60 g of Davison 948 silica dried to 600° C. The resulting slurrywas stirred for 1.5 hours at 25° C. Then a solution of 0.41 g ofN,N-bis(2-hydroxylethyl) octadecylamine in 50 cm³ toluene was added, andstirring continued for another 30 minutes. The final catalyst was thendried to free-flowing powder under vacuum at 65° C.

Polymerization

A sample of the dry catalyst formed in Example 2 was then used in apolymerization process of ethylene/1-butene in a 2-liter semi-batchgas-phase reactor at 85° C. The pressure in the reactor, about 158 psig(1089 kPag), was held constant by continuously feeding 5 mol-% 1-butenein ethylene to compensate for any pressure change due to polymerization.After 1 h, the polymer formed was separated from the seed bed materialand analyzed for the molecular properties shown as Run 3 in Table 1below.

Example 3 Preparation of Catalyst

Methylalumoxane (MAO) (1155 cm³ of 30 wt-% solution in toluene) wascharged into a 2-gallon reaction vessel. 1970 cm³ of fresh toluene wasadded. Then a solution of 20.2 g of bis(n-propylcyclopentadienyl)hafnium dichloride in 355 cm³ toluene was added. The temperature wasmaintained at 27° C. and the mixture stirred for 1.5 hour. A 1000 g of aDavison 948 silica dehydrated at 600° C. was charged into a 2-gallonreaction vessel at 27° C. The solution of methylalumoxane andmetallocene from above was added onto the silica in two equal portions.Then an additional 250 cm³ toluene was added to the slurry. After 1hour, a solution of 6.7 g of N,N-bis(2-hydroxylethyl) octadecylamine in70 cm³ toluene was added and stirring continued for another 20 minutes.The final catalyst was then dried to free-flowing powder at 68° C. undervacuum.

Polymerization

Samples of the dry catalyst formed in Example 3 each were then used in apolymerization process of ethylene/1-butene in a 2-liter semi-batchgas-phase reactor at 85° C. The pressure in the reactor, about 158 psig(1089 kPag), was held constant by continuously feeding 5 mol-% 1-butenein ethylene to compensate for any pressure change due to polymerization.After 1 h, the polymer formed was separated from the seed bed materialand analyzed for the molecular properties shown as Runs 4-6 in Table 1below.

Example 4 Preparation of Catalyst

A solution of methylalumoxane and metallocene was formed by adding 27.8cm³ of 30 wt-% MAO solution in toluene onto 0.536 g ofbis(n-butylcyclopentadienyl) hafnium dichloride in a vial. 60 cm³ offresh toluene was added, and the mixture stirred for 1.5 hours at 25° C.This pre-mixed solution of the MAO and the metallocene was then addedonto 25 g of Davison 948 silica dried to 600° C. The resulting slurrywas stirred for 1.5 hours at 25° C. Then a solution of 0.166 g ofN,N-bis(2-hydroxylethyl) octadecylamine in 40 cm³ toluene was added, andstirring continued for another 30 minutes. The final catalyst was thendried to free-flowing powder under vacuum at 65° C.

Polymerization

Samples of the dry catalyst formed in Example 4 then were each used in apolymerization process of ethylene/1-butene in a 2-liter semi-batchgas-phase reactor at 85° C. The pressure in the reactor, about 155 psig(1069 kPag), was held constant by continuously feeding 5 mol-% 1-butenein ethylene to compensate for any pressure change due to polymerization.After 1 h, the polymer formed was separated from the seed bed materialand analyzed for the molecular properties shown as Runs 7-9 in Table 1below.

Comparative Example 5 Preparation of Catalyst

A solution of methylalumoxane and metallocene was formed by adding 27.7cm³ of 30 wt-% MAO solution in toluene onto 0.413 g ofbis(cyclopentadienyl) hafnium dichloride in a vial. 50 cm³ of freshtoluene was added, and the mixture stirred for 1.5 hours at 25° C. Thispre-mixed solution of the MAO and the metallocene was then added onto 25g of Davison 948 silica dried to 600° C. The resulting slurry wasstirred for 1.5 hours at 25° C. Then a solution of 0.166 g ofN,N-bis(2-hydroxylethyl) octadecylamine in 40 cm³ toluene was added, andstirring continued for another 30 minutes. The final catalyst was thendried to free-flowing powder under vacuum at 65° C.

Polymerization

Samples of the dry catalyst formed in Comparative Example 5 were theneach used in a polymerization process of ethylene/1-butene in a 2-litersemi-batch gas-phase reactor at 85° C. The pressure in the reactor,about 158 psig (1089 kPag), was held constant by continuously feeding 5mol-% 1-butene in ethylene to compensate for any pressure change due topolymerization. After 1 h, the polymer formed was separated from theseed bed material and analyzed for the molecular properties shown asRuns C1 and C2 in Table 1 below.

Comparative Example 6 Preparation of Catalyst

A solution of methylalumoxane and metallocene was formed by adding 27.8cm³ of 30 wt-% MAO solution in toluene onto 0.444 g of bis(methylcyclopentadienyl) hafnium dichloride in a vial. 60 cm³ of freshtoluene was added, and the mixture stirred for 1.5 hours at 25° C. Thispre-mixed solution of the MAO and the metallocene was then added onto 25g of Davison 948 silica dried to 600° C. The resulting slurry wasstirred for 1.5 hours at 25° C. Then a solution of 0.169 g ofN,N-bis(2-hydroxylethyl) octadecylamine in 50 cm³ toluene was added, andstirring continued for another 30 minutes. The final catalyst was thendried to free-flowing powder under vacuum at 65° C.

Polymerization

A sample of the dry catalyst formed in Comparative Example 6 was thenused in a polymerization process of ethylene/1-butene in a 2-litersemi-batch gas-phase reactor at 85° C. The pressure in the reactor,about 154 psig (1062 kPag), was held constant by continuously feeding 5mol-% 1-butene in ethylene to compensate for pressure changes due topolymerization. After 1 h, the polymer formed was separated from theseed bed material and analyzed for the molecular properties shown as RunC3 in Table 1 below.

Comparative Example 7 Preparation of Catalyst

A solution of methylalumoxane and metallocene was formed by adding 27.8cm³ of 30 wt-% MAO solution in toluene onto 0.475 g ofbis(ethylcyclopentadienyl) hafnium dichloride in a vial. 60 cm³ of freshtoluene was added, and the mixture stirred for 1.5 hours at 25° C. Thispre-mixed solution of the MAO and the metallocene was then added onto 25g of Davison 948 silica dried to 600° C. The resulting slurry wasstirred for 1.5 hours at 25° C. Then a solution of 0.167 g ofN,N-bis(2-hydroxylethyl) octadecylamine in 50 cm³ toluene was added, andstirring continued for another 30 minutes. The final catalyst was thendried to free-flowing powder under vacuum at 65° C.

Polymerization

A sample of the dry catalyst formed above in Comparative Example 7 wasthen used in a polymerization process of ethylene/1-butene in a 2-litersemi-batch gas-phase reactor at 85° C. The pressure in the reactor,about 160 psig (1103 kPag), was held constant by continuously feeding 5mol-% 1-butene in ethylene to compensate for any pressure change due topolymerization. After 1 h, the polymer formed was separated from theseed bed material and analyzed for the molecular properties shown as RunC4 in Table 1 below.

Comparative Example 8 Preparation of Catalyst

A solution of methylalumoxane and metallocene was formed by adding 28cm³ of 30 wt-% MAO solution in toluene onto 0.585 g of Me₂Si (Indenyl)₂hafnium dichloride in a vial. 60 cm³ of fresh toluene was added, and themixture stirred for 1.5 hours at 25° C. This pre-mixed solution of theMAO and the metallocene was then added onto 25 g of Davison 948 silicadried to 600° C. The resulting slurry was stirred for 1.5 hours at 25°C. Then a solution of 0.167 g of N,N-bis(2-hydroxylethyl) octadecylaminein 40 cm³ toluene was added, and stirring continued for another 30minutes. The final catalyst was then dried to free-flowing powder undervacuum at 65° C.

Polymerization

Samples of the dry catalyst formed above in Comparative Example 8 werethen each used in a polymerization process of ethylene/1-butene in a2-liter semi-batch gas-phase reactor at 85° C. The pressure in thereactor, about 158 psig (1089 kPag), was held constant by continuouslyfeeding 5 mol-% 1-butene in ethylene to compensate for any pressurechange due to polymerization. After 1 h, the polymer formed wasseparated from the seedbed material and analyzed for the molecularproperties shown as Runs C5-C7 in Table 1 below.

TABLE 1 Catalyst Polymer Density I₂ I₂₁ Run # (mg) Yield (g) Activity¹(g/cc) (dg/min) (dg/min) Mw MWD (nPrCp)₂HfCl₂ 1 100 211 2126 0.90610.096 2.26 278942 2.88 2 50 117 2363 0.9025 0.089 2.5 275100 2.61 3 50136 2674 NM NM 1.83 NM NM 4 50 159 3159 0.9064 NM 1.76 283282 2.82 5 50117 2325 0.9091 NM 1.77 272925 2.80 6 50 117 2356 0.9081 NM 2.0 3168012.88 (nBuCp)₂HfCl₂ 7 150 271 1821 0.9057 NM 1.2 322890 2.46 8 150 2251479 0.9056 NM 0.83 NM NM 9 100 195 1935 0.9070 NM 1.51 NM NM (Cp)₂HfCl₂C1 300 12 40 0.9310 NM 0.42 361692 3.98 C2 500 18 36 0.9273 NM 0.67 NMNM (MeCp)₂HfCl₂ C3 150 17 112 0.9234 NM 0.68 291412 3.24 (EtCp)₂HfCl₂ C4150 16 107 0.9275 NM 0.36 375772 3.20 Me₂Si(Ind)₂HfCl₂ C5 150 7 480.9365 NM 1.74 232475 3.44 C6 150 6 37 0.9265 NM 1.21 263758 4.16 C7 50025 49 0.9239 NM 1.73 239161 3.40 Note ¹Catalyst activity expressed asg_(PE)/(g_(CAT)·h ·150 psi) NM—Not Measured; “Ind” is indenyl

Example 9 Preparation of Catalyst

Methylalumoxane (1155 cm³ of 30 wt % solution in toluene) was chargedinto a 2-gallon reaction vessel. 1970 cm³ of fresh toluene was added.Then a solution of 20.17 g of a bis(n-propyl cyclopentadienyl)transition metal dichloride, wherein the transition metal comprised 99.1mole % Hf (hafnocene) and 0.9 mole % Zr (zirconocene), in 250 cm³toluene was added. The temperature was maintained at 27° C. and themixture was stirred for 1.5 hours. 998.8 g of a Crossfield 40/600 Csilica (dehydrated a 600° C.) was charged into a 2-gallon reactionvessel at 27° C. The solution of methylalumoxane and metallocene fromabove was added onto the silica in two equal portions. Then anadditional 250 cm³ of toluene was added to the slurry. After 1 hour, asan antistatic agent, 6.71 g of N,N-bis(2-hydroxyethyl) octadecylamine in85 cm³ toluene was added and stirring continued for another 20 minutes.The final catalyst was then dried to a free-flowing powder under vacuumfor 12 hours of drying time. Theoretical solids (dry wt) recovery is1337 g; actual final yield (dry wt) was 1160.6 g for an 87% recovery. Ofthese solids 11.11 wt % was Al, the Al to transition metal molar ratiowas 125 and the transition metal loading as Hf was 0.66 wt % and as Zrwas 0.003 wt %.

Polymerization

Samples of the dry catalyst formed in Example 9 were then used in apolymerization process of ethylene/1-hexene in a pilot plant semi-batchgas-phase reactor at 85° C. under conditions and with results asreported in Table 2 below.

TABLE 2 RUN NUMBER 3-14 3-15 3-16 Reaction Temperature (° C.) 85 85 85(averaged) Run Time (hrs) 58 35 41 Number Bed Turnovers 19.01 5.97 3.35Catalyst Feed Rate 30 26 22 Reaction Atmosphere H₂ (ppm) 508.2 554.9171.9 Ethylene (mole %) 70.0 69.9 66.1 1-Hexene (mole %) 1.02 1.01 1.02Nitrogen (mole %) 28.98 29.09 32.88 Pressure (psig) 300/2067 300/2067300/2067 Production Rate (lbs/hr) 58.8/24  63.5/26  59.8/24  SpecificActivity (g/g-hr-atm) 60 64 53 Polymer Properties MI (g/10 min.) 1.113.39 0.11 MIR 24.82 23.17 28.17 Density (g/cc) 0.9162 0.9175 0.9115 BulkDensity (g/cc) 0.4088 0.4036 0.4048 Ash (ppm) 243 229 292 Hf (ppm) 1.2811.263 1.619 Al (ppm) 17.4 14.9 19.9

Example 10

Quantities of the ethylene copolymer resin product granulas produced byRuns 3-14 and 3-15 of Table 2 of Example 9 were taken from a breadturnover mixed with granules taken from other bed turnovers and then,with an added antioxidant agent, extruded then chopped into pellets.These resin pellets were then analyzed for their molecular propertiesbefore pellets of resins were converted into film articles. The resinpellets of Run 3-15 having an MI of 2.9 were cast extruded into a filmwhile the resin pellets of Run 3-14 having a MI of 1 being were madeinto a film by a blown bubble technique.

For comparative purposes the ethylene copolymer resin of MI about 2.9 ofRun 3-15 was compared to films similarly cast from Dow ELITE™ 5200 andExxon EXCEED™ 357 C32, both of which are ethylene copolymers having anMI of about 3. Similarly, for comparative purposes the ethylenecopolymer resins of Run 3-14 having an MI of about 1 was compared toblown bubble films similarly produced from Dow ELITE™ 5400 and ExxonEXCEED™ 350D60, both of which are ethylene copolymers having an MI ofabout 1.

This comparison of cast and blown bubble films prepared from theethylene copolymers of the invention, in particular, the LLDPE resins ofthis invention, to cast and blown bubble films produced from a DowELITE™ or Exxon EXCEED™ resin of similar resin density and MI value ispresented below.

The specific properties of these cast film resins and their resultingfilm articles as formed, as also as each is time aged and heat aged (asin the case of article inventory storage) are reported in Tables 3-5below.

TABLE 3A CAST FILMS Resin Run Elite ™ Exceed ™ Resin Properties 3-155200 357C32 MI (g/10 min) 2.9 3.4 3.4 MIR 22.5 23.0 16.7 Resin density(g/cc) 0.9177 0.9197 0.9183 Mw (×1000) 94.2 76.6 84.8 MWD (M_(w)/M_(n))3.48 3.4 2.45 M_(z)/M_(w) 2.23 2.6 1.80 Hexene mole % (bulk) 3.6 2.7 3.1Melt Strength (Cn) 1.82 NM 1.2 T.R.E.F. low-T peak ° C. 63 62 N/A est.low-T peak mole % 73 53 N/A low-T peak hexane mole % 5.82 6.01 N/AIntermediate-T peak ° C. N/A 79 73 est. I-T peak mole % N/A 30 100 I-Tpeak hexene mole % N/A 2.88 3.91 High-T peak ° C. 82 90 N/A est. H-Tpeak mole % 27 17 N/A H-T peak hexene mole % 2.30 0.83 N/A

TABLE 3B Resin Run Elite ™ Exceed ™ Film Properties 3-14 5200 357C32Film Gage (mil) 0.83     0.83 0.83 Film Density (g/cc) 0.9104     0.91210.9101 1% Sec. Mod. (psi) MD 15,400 22,300   14,950 TD 18,780 25,250  20,570 Tensile (psi) @ Yield MD 821 1,000  954 TD 806 970 938 @ Break MD9,982 9,913  8,896 TD 6,227 5,350  5,154 Elongation (%) @ Yield MD 4.7  5.0 4.4 TD 6   4.9 4.6 @ Break MD 365 364 446 TD 673 616 793 Tear ±“SD” (g/mil) MD 252 ± 43 183 185 ± 26 TD 620 ± 53 773 615 ± 53 IntrinsicTear (g/mil) — 530 ca. 460 26″ Dart ± SD (g/mil) 460 ± 30 212 ± 31^(§)648 ± 76 Haze (%) 1   0.6 2.1 45° Gloss 92.6  92 88.8 Film ExtensionProperties Rate (lb/h/rpm) 5.90     5.85±± 6.10 E.S.O. (lb/hp/h) 6.95    7.37±± 6.36 Act./max Extr. Amp 204/240 180/240 225/240 Head Pressure(psi) 3941  2900±± 4167

Table 4 here below reports the differentiation in cast film propertiesupon 6 months aging of the inventive and comparative films reported asin Table 3B above. In Table 4 the Δ number is the differential value inthe change of film properties from those of an initial cast unaged film.

TABLE 4 Cast Films, Six Month Aged Film Properties Run 3-15 Exceed ™57C32 Film gage (mil) 0.82 (Δ0.01) 0.83 (Δ = 0) Film density (g/cc)0.9104 (Δ = 0) 0.9102 (Δ = .0001) 1% Sec. Mod. (kpsi) MD 16.1 (Δ = 0.7)16.2 (Δ = 1.25) TD 20.0 (Δ = 1.22) 17.9 (Δ = −2.67) Tear ± SD (g/mil) MD367 (Δ = 115 ± 20) 166 (Δ = −19 ± 21.5) TD 617 (Δ = −3 ± 44.5) 555 (Δ =−60 ± 46) 26″ Dart ± SD 446 (Δ = −14 ± 46.5) 517 (Δ = −131 ± 78.5)Shrink MD 60 (Δ = +4) 54 (Δ = −7) TD 16 (Δ = 28) 9 (Δ = 10)

Produced films (inventive and comparisons) were heat aged by holding aroll of such film at 140° F. (64.4° C.) for 48 hours, and thereafterremoving such film roll to room temperature (ambient) and equilibriatingsame to ASTM conditions (except for that of relative humidity). For castm LLDPE resin films of this invention in comparison to Dow ELITE™ 5200and/or Exxon EXCEED™ 357C32 resin cast films, similarly cast and heataged, Table 5 below reports the difference in certain film properties(i.e., in the table; reported as “Δ=” either at a positive or negativevalue as against the property value measured for the initially producedfilm).

TABLE 5 Heat Aged Cast Film Run Elite ™ Exceed ™ Film Properties 3-155200 357C32 Film Gage (mil) 0.83 (Δ = 0) 0.83 (Δ = 0) 0.83 (Δ = 0) FilmDensity (g/cc) 0.9130 (Δ = 0.0026) 0.9121 (Δ = NM) 0.9125 (Δ = 0.0024)1% Sec. Mod. (kpsi) MD 17.23 (Δ = 1.8) 19.3 (Δ = −3) 15.78 (Δ = 0.83) TD21.32 (Δ = 2.54) 27.3 (Δ = 2.05) 19.9 (Δ = −0.67) Tensile (psi) @ YieldMD 1149 (Δ = 328) 1014 (Δ = 14) 1107 (Δ = 153) TD 1091 (Δ = 285) 970 (Δ= 119) 1037 (Δ = 99) @ Break MD 9856 (Δ = −126) 9238 (Δ = −675) 9833 (Δ= 937) TD 6220 (Δ = −7) 5368 (Δ = 18) 7191 (Δ = 2037) Elongation (%) @Yield MD 7.3 (Δ = 2.6) 4.3 (Δ = −0.7) 7.4 (Δ = 3.0) TD 6.0 (Δ = 0.4) 4.5(Δ = −0.4) 6.3 (Δ = 1.7) @ Break MD 370 (Δ = 5) 351 (Δ = −13) 417 (Δ =−29) TD 704 (Δ = 31) 633 (Δ = 17) 711 (Δ = −82) Tear ±SD (g/mil) MD 138(Δ = −114 ± 335) 391 (Δ = 208) 136 (Δ = −49 ± 22) TD 778 (Δ = 158 ± 53)827 (Δ = 57) 615 (Δ = 0 ± 43) 26″ Dart ± SD 648 (Δ = 188 ± 53) 212 (Δ =−88) 187 (Δ = −461 ± 50)

As also reported by this Example, blown bubble film articles wereprepared from MI±1 (LLDPE resin of this invention and alsocomparison≅MI=1 resins of ELITE™ and EXCEED™. The specific properties ofthese blown film resins and their resulting film articles as formed arereported in Table 6 below.

TABLE 6A BLOWN FILMS Resin Run Elite ™ Exceed ™ Resin Properties 3-145400 350D60 MI (g/10 min) 1.0 1.26 0.98 MIR 23.5 26.0 16.3 Resin density(g/cc) 0.9167 0.9168 0.9186 Mw (×1000) 131 98.9 106(+)  MWD(M_(w)/M_(n)) 3.28 3.3 1.4(+) M_(z)/M_(w) 2.24 2.4 1.8(+) Hexene mole %(bulk) 3.3 3.5 2.6 Melt Strength (cN) T.R.E.F. low-T peak ° C. 65 58 N/Aest. low-T peak mole % 72 37 N/A low-T peak hexene mole % 5.44 6.75 N/AIntermediate-T peak ° C. N/A 76 76 est. I-T peak mole % N/A 53 100 I-Tpeak hexene mole % N/A 3.39 3.38 High-T peak ° C. 82 90 N/A est. H-Tpeak mole % 27 10 N/A H-T peak hexene mole % 2.30 0.76 N/A

TABLE 6B Resin Run Elite ™ Exceed ™ Film Properties 3-14 5400 350D60Film Gage (mil) 1.00 0.74 1.00 Film Density (g/cc) 0.9140 0.9142 0.91561% Sec. Mod. (psi) MD 26,400 25,280 28,600 TD 32,100 29,500 30,900Tensile (psi) @ Yield MD 1244 1117 1250 TD 1265 1190 1328 Tensile @Break MD 7782 8863 8485 TD 9755 7856 10,026 Elongation (%) @ Yield MD4.7 4.2 4.8 TD 4.7 4.4 4.9 Elongation @ Break MD 424 440 465 TD 624 569644 Tear ± “SD” (g/mil) MD 238 ± 22 273 249 ± 24 TD 495 ± 17 526 500 ±25 Intrinsic Tear (g/mil) ca 390 510 390 26″ Dart ± SD (g/mil) 1238 ±114 1237 ± 105^(§) 927 ± 84 Haze (%) 13.1 7.1 12.6 45° Gloss 44 58 39Film Extrusion Properties Rate (lb/h/rpm) (_/h/rpm) 3.3 6.2 3.2 E.S.O.(lb/hp/h) (_/h/rpm) 11.6 13.4 9.96 Act./max Extr. Amp 68.6/125 170/24074/129 Head Pressure (psi) (kPa) 3490 5310 3650

While the present invention has been described and illustrated byreference to particular embodiments, those of ordinary skill in the artwill appreciate that the invention lends itself to variations notnecessarily illustrated herein. It is contemplated that the catalystsystem of this invention can be used in combination with other catalystsystems comprising more than one catalyst system of the invention. Forthis reason, then, reference should be made solely to the appendedclaims for purposes of determining the true scope of the presentinvention. Various changes in the details of the illustrated apparatusand construction and method of operation may be made without departingfrom the spirit of the invention.

1. An ethylene copolymer having a polymodal CD, wherein undertemperature rising elution fractionation (TREF) analysis the ethylenecopolymer evidences at least two peaks and wherein the ethylenecopolymer has an I₂₁/I₂ value of from 15 to 100 and the ethylenecopolymer is produced by polymerizing ethylene in the presence of ahafnium metallocene catalyst compound and the ethylene copolymercomprises less than about 0.01 ppm to about 5 ppm hafnium.
 2. Theethylene copolymer of claim 1, having an M_(z)/M_(w) ratio of at least2.
 3. The ethylene copolymer of claim 1, having an Mw/Mn value of from2.5 to about
 7. 4. The ethylene copolymer of claim 1, comprising about0.01 ppm to about 2 ppm hafnium.
 5. The ethylene copolymer of claim 1,wherein under temperature rising elution fractionation (TREF) analysisexhibits a low-temperature peak position at from 45-75° C.
 6. Theethylene copolymer of claim 1, wherein under temperature rising elutionfractionation (TREF) analysis exhibits a low-temperature peak positionat about 65° C.
 7. The ethylene copolymer of claim 1, wherein undertemperature rising elution fractionation (TREF) analysis exhibits a peakseparation between the low-temperature and high-temperature peaks of aminimum of about 20° C. and a maximum of about 35° C.
 8. The ethylenecopolymer of claim 1, wherein under temperature rising elutionfractionation (TREF) analysis exhibits low-temperature peak ranges fromabout 10 mole % to a maximum of about 90 mole % of the copolymer.
 9. Theethylene copolymer of claim 1, wherein under temperature rising elutionfractionation (TREF) analysis exhibits low-temperature peak ranges fromabout 30 mole % and the high-temperature peak is about 70 mole %. 10.The ethylene copolymer of claim 1, having an I₂₁/I₂ value of from 18 to50.
 11. The ethylene copolymer of claim 1 having a density of from about0.86 to 0.97 g/cc.
 12. A film made from the ethylene copolymer ofclaim
 1. 13. An ethylene copolymer of claim 1, wherein the ethylenecopolymer is produced in a single reactor.
 14. The ethylene copolymer ofclaim 13, wherein the reactor is a gas phase reactor.
 15. A film madefrom the ethylene copolymer of claim
 13. 16. An ethylene copolymerhaving a polymodal CD, wherein the ethylene copolymer is produced in asingle reactor by polymerizing ethylene in the presence of a hafniummetallocene catalyst compound; wherein under temperature rising elutionfractionation (TREF) analysis the ethylene copolymer evidences at leasttwo peaks; wherein the ethylene copolymer has an Mw/Mn of from about 2.5to about 7; wherein the ethylene copolymer has a density of from 0.905to 0.95 g/cc; wherein the ethylene copolymer has a an I₂₁/I₂ value offrom 15 to 100; wherein the ethylene copolymer exhibits alow-temperature peak position at about 65° C. under temperature risingelution fractionation (TREF) analysis; wherein the ethylene copolymerexhibits a peak separation between the low-temperature andhigh-temperature peaks of a minimum of about 20° C. and a maximum ofabout 35° C. under temperature rising elution fractionation (TREF)analysis; wherein the ethylene copolymer exhibits low-temperature peakranges from about 30 mole % and the high-temperature peak is about 70mole % under temperature rising elution fractionation (TREF) analysis;and wherein the ethylene copolymer comprises about 0.01 ppm to about 2ppm hafnium.